Refactored to reduce complexity from O(n^2) to O(n)

Author: SaraTahir28

Sprint-1/JavaScript/removeDuplicates/removeDuplicates.mjs

@@ -1,36 +1,31 @@
-/**
- * Remove duplicate values from a sequence, preserving the order of the first occurrence of each value.
+
+ /**
+ * Remove duplicate values from a sequence, preserving the order of the first occurrence.
  *
  * Time Complexity:
+ *   Before refactoring: O(n^2)
+ *   The original solution used nested loops to check for duplicates.
+ *   After refactoring: O(n)
+ *   Using a Set allows duplicate checks in constant time (O(1)),
+ *   removing the need for the inner loop.
+ *
  * Space Complexity:
- * Optimal Time Complexity:
+ *   Before refactoring: O(n)
+ *   The result array could store up to n unique items.
+ *   After refactoring: O(n)
+ *   The Set and the final array both store up to n unique items.
  *
+ * Optimal Time Complexity:
+ *   O(n) — You must inspect each element at least once, and Set lookups are O(1).
+ * 
  * @param {Array} inputSequence - Sequence to remove duplicates from
  * @returns {Array} New sequence with duplicates removed
  */
 export function removeDuplicates(inputSequence) {
-  const uniqueItems = [];
+  const uniques =new Set() //does dupliacte check in O(1)
 
-  for (
-    let currentIndex = 0;
-    currentIndex < inputSequence.length;
-    currentIndex++
-  ) {
-    let isDuplicate = false;
-    for (
-      let compareIndex = 0;
-      compareIndex < uniqueItems.length;
-      compareIndex++
-    ) {
-      if (inputSequence[currentIndex] === uniqueItems[compareIndex]) {
-        isDuplicate = true;
-        break;
-      }
-    }
-    if (!isDuplicate) {
-      uniqueItems.push(inputSequence[currentIndex]);
-    }
+  for (let i=0 ;i<inputSequence.length;i++){ // O(n)
+    uniques.add(inputSequence[i]);
   }
-
-  return uniqueItems;
-}
+  return Array.from(uniques);
+}